Question

Ethanol is getting wider use as car fuel when mixed with gasoline.3 A car manufacturer wants to evaluate the performance of engines using ethanol mix with that of pure gasoline. The sample average for 100 runs using ethanol is 76.5 on a 0 to 100 scale and the sample standard deviation is 38. For a sample of 100 runs of pure gasoline, the sample average is 88.1 and the standard deviation is 40. Conduct a two-tailed test using α = 0.05, and also provide a 95% confidence interval for the difference between means.